1. Field
The following description relates to a security technology, and more particularly, to security protocol technology of a downloadable conditional access system.
2. Description of the Related Art
With the introduction of downloadable conditional access system (DCAS), cable service subscribers can purchase a set-top box from retailers regardless of multiple system operators (MSOs) from which the subscriber is provided with cable services. In addition, the DCAS enables subscribers to use pay-cable services continuously without need of replacing a set-top box even when changing from one MSO to another. Furthermore, the DCAS allows a subscriber to replace a conditional access system (CAS) with a new CAS manufactured by a different provider without replacing the existing set-top box.
The above advantages can be achieved by the DCAS which allows images of security-required application programs, such as a CAS application, a digital right management (DRM) application and an authorized service domain (ASD) application, to be safely downloaded to secure micro (SM) which is a security chip in the set-top box and also allows the MSO to freely install and replace such applications from sources online.